Process for preparing poly-gamma-methyl glutamate fiber

ABSTRACT

POLY-Y-METHYL GLUTAMATE FIBER HAVING NON-CICULAR CROSSSECTION MAY BE OBTAINED EFFICIENTLY BY A PROCESS, WHICH COMPRISES ADDING CARBON TETRACHLORIDE, 1,1,1 - TRICHLOROETHANE, OR ETHYLENE TETRACHLORIDE TO A SOLUTION OF POLY-YMETHYL GLUTAMATE IN METHLENE CHLORIDE, CHLOROFORM, 1,2DICHLOROETHANE, 1,1,2-TRICHLOROETHANE OR TETRACHLOROETHANE, AND EXTRUDING THE MIXED SOLTUION FROM A CIRCULAR NOZZLE INTO A MIXTURE OF AN ALIPHATIC HYDROCARBON HAVING A BOILING POINT OF 80*C TO 400*C. AND CARBON TETRACHLORIDE, 1,1,1-TRICHLOROETHANE OR ETHYLENE TETRACHLORIDE.

Jan. 19, 1971 YASUO TAKAGI ETAL 3,557,272

PROCESS FOR PREPARING POLY-T-METHYL GLUTAMA'IE FIBER Filed June 24, 1968 10 Sheets-Sheet 1 Jan. 19, 1971 s o TAKAG} EIAL 3,557,272

T-METHYL GLUTAMA'I'E FIBER PROCESS FOR PREPARING POLY- l0 Sheets-Sheet 2 Filed June 24, 1968 A 2 m F c 2 w E:

Jan. 19, 1971 As o TAKAG] E'I'AL 3,557,272

PROCESS FOR PREPARING POLY- METHYL GLUTAMATE FIBER Filed June 24, 1968 1o Sheets-Sheet s Ja'n. 19, 1971 YAsUQ TAKAG] ETAL 3,557,272

PROCESS FOR PREPARING POLY METHYL GLUTAMATE FIBER Filed June 24, 1968 10 Sheets-Sheet 4- Jan. 19, 1971 YASUQ TAKAG] ETAL 3,557,272

PROCESS FOR PREPARING POLY METHYL GLUTAMATE FIBER Filed June 24, 1968 10 Sheets-Sheet 5 FIG. 3F

INVENTOR ATTORNEY Jan. 19, 1971 YASUO TAKAG] ETAL 3,557,272

PROCESS FOR PREPARING POLY-' -METHYL GLUTAMATE FIBER Filed June 24, 1968 10 Sheets-Sheet 6 19, 1971 YA'SUQ TAKAG] EI'AL 3,557,272

METHYL GLUTAMATE FIBER PROCESS FOR PREPARING POLY-r l0 Sheets-Sheet '7 Filed June 24, 1968 Jan. 19, 1971 'sud T K E'IAL 3,557,272

PROCESS FOR PREPARING POLY-' -METHYL GLUTAMATE FIBER Filed June 24, 1968 10 Sheets-Sheet 8 Jan. 19, 1971 YASUO TAKAG] ETAL 3,557,272

PROCESS FOR PREPARING POLY-' -METHYL GLUTAMATE FIBER Filed June 24', 1968 10 Sheets-Sheet 9 Jan. 19, 1971 YASUQ TAKAG| EI'AL 3,557,272

PROCESS FOR PREPARING POLY-T-METHYL GLUTAMATE FIBER Filed June 24, 1968 10 Sheets-Sheet 10 FIG. 6H

FIG. 61

United States Patent 3,557,272 PROCESS FOR PREPARING POLY-'y-METHYL GLUTAMATE FIBER Yasuo Takagi and Makoto Iwatsuki, Kawasaki-shi, Kazuhisa Takeshita, Yokohama-shi, and Isao Uemura, ZllShlshi, Japan, assignors to Ajinomoto Co., Inc., Tokyo,

Japan Filed June 24, 1968, Ser. No. 739,517 Claims priority, application Japan, June 24, 1967, 42/ 40,423 Int. Cl. DOlf 7/00 US. Cl. 264-184 4 Claims ABSTRACT OF THE DISCLOSURE Poly-'y-methyl glutamate fiber having non-circular cross section may be obtained efficiently by a process, which.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1; (a) is a cross-section photograph of polymethyl glutamate (hereinafter, referred to as PMG) fiber which was obtained by extruding a PMG solution in methylene chloride-ethyl acetate mixture consisting mainly of methylene chloride into an acetone coagulating bath, (b) is a cross-section photograph of PMG fiber which was obtained by extruding a PMG solution in 1,2 dichloroethane into a methyl ethyl ketone coagulating bath, and (c) is a cross-section photograph of PMG fiber which was obtained by extruding a PMG solution in methylene chloride-dioxane mixture consistingly mainly of methylene chloride into an acetone-methanol mixture coagulating bath.

FIG. 2; (a)(f) are cross-section photographs of PMG fibers which correspond respectively to samples (a)(f) in Table 1 of this specification.

FIG. 3; (a)( g) are cross-section photographs of PMG fibers which correspond respectively to samples (a)-( g) in Table 4 of this specification.

FIG. 4; (a) and (b) are cross-section photographs of PMG fibers which correspond respectively to samples (a) and (b) in Table 5 of this specification.

FIG. 5; (a)(c) are cross-section photographs of PMG fibers which correspond respectively to samples (a)(c) in Table 6 of this specification.

FIG. 6; (a)(i) are cross-section photographs of PMG fibers which correspond respectively to samples (a)(i) in Table 7 of this specification.

BACKGROUND OF THE INVENTION The present invention relates to a process for preparing poly-'y-methyl glutamate (hereinafter, referred to. as PMG) fiber having non-circular cross-section.

Among all synthetic fibers proposed heretofore, PMG fiber is most similar to natural silk fiber with respect to physical properties, appearance and touch since PMG contains the same peptide linkage as natural silk.

Especially, PMG fiber having non-circular cross-section closely resembles natural silk fiber in its touch compared to PMG fiber having circular cross-section.

Various processes have been proposed heretofore for preparing PMG fiber by wet spinning. For example, (1) Japanese patent publication No. 5,926/1965 discloses a ice process for preparing PMG fiber by extruding a PMG solution into a coagulating bath containing acetone, ethyl acetate or their mixture, the PMG being dissolved in a methylene chloride-ethyl acetate mixture which consists mainly of methylene chloride. (2) Japanese patent publication No. 27,363/1965 describes a process for preparing PMG fiber, which comprises extruding a PMG solution into a coagulating bath containing acetone (90-60 percent by volume) and methanol (1040 percent by volume), the PMG being dissolved in a methylene chlorideethyl acetate mixture or methylene chloride-dioxane mixture, each of which consists mainly of methylene chloride, and (3) there is disclosed in Japanese patent publication No. 6,608/ 1966 a process for preparing PMG fiber by extruding a PMG solution in halogenated aliphatic hydrocarbon such as methylene chloride, chloroform or 1,2-dichloroethane into a coagulating bath containing acetone, methyl ethyl ketone, lower aliphatic alcohol, diethyl ether, petroleum ether or mixtures of these coagulating liquids.

It has been found that the PMG fibers obtained according to each of the above known processes by using a circular nozzle which is usually applied in wet spinning have approximately circular cross-sections and PMG fabrics made therefrom have a dilferent touch from the characteristic one of natural silk fiber.

FIG. 1 (a)(c) are cross-section photographs of wetspun PMG fibers obtained according to the known processes under the following respective spinning conditions:

Spinning solvent: Methylene chloride/ethyl acetate mixture=l2/5 (by volume) Polymer concentration: 15 percent by weight Coagulating agent: Acetone Spinning solvent: 1,2-dichloroethane Polymer concentration: 10 percent by weight Coagulating agent: Methyl ethyl ketone Spinning solvent: Methylene chloride-dioxane=8/2 (by volume) Polymer concentration: 7 percent by Weight Coagulating agent: Acetone/methanol=/25 (percent by volume) In the melt spinning of polyester or polyamide fibers, fibers having non-circular cross-sections are obtained from a nozzle with Y or X shaped cross-section. The crosssectional shape of the fiber depends on the shape of the nozzle opening. However, a nozzle of non-circular crosssection is very expensive compared to one with circular cross-section. In addition, it is impossible to make a nozzle opening of a very small cross-section as is possible in a nozzle of circular cross-section.

In fact, a nozzle with non-circular cross-section cannot be used'for preparing PMG filament of low denier by the known processes, since the maximum stretching ability of PMG fiber is very small in comparison with those of other synthetic fibers.

Economic considerations require that the spinning solution be spun at as high velocity as possible without loss of textile properties. The coagulating agents used hitherto in the wet spinning of PMG fibers are acetone, methyl ethyl ketone, ethyl acetate, lower alcohols, ethers, petroleum ether and mixtures of these compounds, as disclosed in Japanese patent publication Nos. 5,926/1965, 27,369/ 1965 and 6,608/ 1966. Since each of these coagulants is a combustible solvent having a low flash point, the spinning process is very dangerous. Therefore, expensive equipment for preventing fire and explosion and careful safety supervision are necessary.

3 SUMMARY OF THE INVENTION We have found that a spinning solution of PMG in non-combustible methylene chloride, chloroform, 1,2- dichloroethane, 1,1,2-trichloroethane or tetrachloroethane can be coagulated by means of non-combustible carbon tetrachloride, 1,1,1-trichloroethane and ethylene tetrachloride, and that the PMG solution when wet-spun through a circular type nozzle into a coagulating bath of 4 tetrachloride or 1,1,l-ti'ichloroethane or ethylene tetrachloride as the coagulating agent results in a PMG fiber of improved mechanical properties and of non-circular cross-section.

Table 1 shows the physical properties of the PMG fibers obtained by extruding a PMG solution in 1,2-dichloroethane into various coagulating agents. The crosssections of the PMG fibers are shown in FIG. 2.

Lig/ioin/ethylene tetrachloride= NOTE:

Spinning solvent: 1,2-dichloroethane.

Intrinsic viscosity [1 2,6 (in dichloroacetlc acid at 30 0.). Polymer concentration: 13 percent by weight.

Spinning velocity: 50 meters/minute.

Pull-off Ratio: 1.0 (hereinafter referred to as P.O.R.).

aliphatic hydrocarbons having a boiling point of 80 C. to 400 C. such as ligroin, kerosene and light oil, yields PMG fiber of a cross-section very different from the shape of the nozzle used. However, the PMG fiber obtained by using each of the two coagulating agents alone has unsatisfactory tensile properties such as tenacity and elongation.

The maximum spinnable P.O.R. can be greatly increased by mixing the PMG solution with carbon tetrachloride or 1,1,l-trichloroethane or ethylene tetrachloride which itself is a coagulating agent.

The relationship between coagulating agent content in the spinning solution and maximum spinnable P.O.R. is shown in Table 2.

TABLE 2 [Solvent in PMG solution: 1,1,2trichloroctliane Carbon tetrachloride content, percent by weight Percentage corresponding to the maximum content 0 7. 6 15. 1 30.2 45. 3 60.4 75. 5 90. 6 Maximum spinnable P.O.R 1. 6 1. 8 2. 1 2.6 3.0 3. 2 3. 8 3. 9

(Solvent in PMG solution: methylene chloride 1,1,1-trich1oroethanc content, percent Percentage corresponding to the maximum content 0 8.3 16. 6 33. 2 49.8 66.4 83.0 91. 2 Maximum spinnableP.O.R 1. 2 1. 5 1.9 2. 4 2.8 3.0 3. 1 3. 6

[Solvent in PMG solution: 1,2-dichloroethane Ethylene tetrachloride content, percent Percentage corresponding to the maxi mum content 0 13. 3 26. 6 33. 9 53. 2 66. 5 67. 8 93. 2 Maximum spinnable P.O.R 2. 5 2.8 3. 3 3. 6 4. 0 4. 2 4. 4 4. 5

1 Polymer concentration: 10 percent by weight; Intrinsic viscosity [1 2.3 (in dichloroj acetic acid at 30 0.; Coagulating bath: kerosene/carbon tetrachloride=60l40 (by volume) 1 Spinning velocity: 80 meters/minute.

2 Eolyrner concentration: 9.5 percent by weight; Intrinsic viscosity l]: 2.7 (in dichloroacetic acid at 30 0.; Coagulating bath: light oil/ethylene tetrachloride=40l60 (by volume percent); Spinning velocity: 80 meters/minute.

It has been further found that carbon tetrachloride,-

1,1,l-trichloroethane or ethylene tetrachloride may be added to the PMG solution in chlorinated hydrocarbons to such an extent as not to cause gelation of the PMG solution, and that the modified solution may be spun by extrusion into a coagulating bath containing a mixture of an aliphatic hydrocarbon having a boiling point of from 80 C. to 400 C., and carbon tetrachloride or 1,1,1-trichloroethane or ethylene tetrachloride. The PMG fiber obtained has non-circular cross-section and superior physical properties, and the shape of the cross-section may be widely varied according to the concentration of aliphatic hydrocarbons in the coagulating bath.

Any aliphatic hydrocarbon may be used as one component of the coagulating bath in the present process, if it has a boiling point of 80 C. to 400 C. Representative examples of such aliphatic hydrocarbons are ligroin, kerosene and light oil, which are unexpensively and readily available by fractional distillation of petroleum.

The mixture of an aliphatic hydrocarbon with carbon carbon tetrachloride, 1,1,l-trichloroethane or, ethylene tetrachloride can be mixed with the PMG solution to yield a homogeneous and stable solution suitable for spinning. According to the present invention, a concentrated spinning solution may be prepared by mixing carbon tetrachloride, 1,1,l-trichloroethane or ethylene tetrachloride with a concentrated PMG solution in chlorinated hydrocarbons.

The amount of carbon tetrachloride, 1,1,1-trichloroethane or ethylene tetrachloride necessary to maintain a homogeneous solution in admixture with the PMG solution may be varied according to the degree of polymerization of the PMG, the polymer concentration and the temperature. Table 3 shows the maximum concentrations of the coagulating agents in the PMG solution.

l amount necessary to bring about gelation of 13.5 percent by weight PMG solution having an intrinsic viscosity (1,) of 2.3-2.7 (in dichloroacetic acid at 30 C.) at 25 C. (coagulating agent amount in the total amount of solvents is represented in percent by weight.

According to the present invention, a P.O.R. value above 3.0 may be obtained, this value being much higher than 2.0-2.8, the highest P.O.R. values obtained hitherto (see Japanese patent publication No. 288/ 1966) and therefore the present process is especially advantageous for the production of PMG fiber of low denier. The high According to the present invention, PMG fibers having various cross-sections can be obtained by varying the composition of the spinning solution and the coagulating bath when extruded from a circular nozzle.

Non-circular nozzles may also be used in the present invention. In this case the cross-section of the PMG fibers is modified by the nozzle used.

The modified cross-section is due to the presence of aliphatic hydrocarbons having a boiling point of from 80 C. to 400 C. and is not caused by other solvents having strong coagulating ability such as methanol, acetone and toluene. FIG. 4 shows photographs of PMG fiber obtained with methanol or acetone-ethylene tetrachloride mixture described in Table 5 as the coagulating agent.

TABLE 5 (a) methanol.

P.O.R. value may be maintained even at an extrusion 20 acetone-ethylene t t a l ride 1:1 speed of 80 meters/minute and spinning at more than NOTE,

300 meters/ minute is readily possible in the present process. At a P.O.R. value of 2.0 to 2.8 the extrusion speed Spinning solvent: 1 2 dich1oroethane/ethy1ene.

of the known process was limited to about 30 meters/ Tetrachloridezmmo (percent by volume) minute. 25

Although spun at very high P.O.R., the PMG fiber of the invention has desirable textile properties as is apparent from Table 4 and PMG fibers having non-circular cross-section can be obtained from a circular nozzle even Polymer concentration: 10 percent by weight. Intrinsic viscosity [1 ]=2.6 (in dichloroacetic acid at 30 C.).

The relationship between the composition of the coaguat high spinning velocity and high P.O.R. (see FIG. 3). 30 lating bath and the textile properties of the PMG fiber is TABLE 4 P.O.R.

Elonga- Elonga- Elonga- Elonga- Elonga Composition of coagulating Maximum Tenacity, tion, Tenacity, tion, Tenacity, tion, Tenacity, tion, Tenacity, tion bath 1 P.O.R g./denier percent gJdenrer percent g./denier percent g./denier percent gJdenier percent 1 Percent by volume (ligroin/ethylene tetrachloride).

*a-g: Cross-sections are shown in Fig. 3.

Nora: spinning solvent: 1,2-dichloroethane/ethylene tetrachloride=65l35 polymer concentration: 10 percent by weight intrinsic viscosity [1 ]=2.6 (in dichloroacetic acid at 30C) spinning velocity: 50 meters/minute nozzle: circular type 0.08 mm/2OH.

the coagulating bath is preferably 10-90 percent by 05 shown in Table 6. :It will be understood from the data in Table 6 that the maximum allowable concentration of the PMG solvent in the coagulating bath is as high as based on the total amount of coagulating agent. On the contrary, in the known process described in Japanese patent publication No. 27,369/ 1965, the maximum allowable concentration of the PMG solvent in the coagulating bath is 15%. Thus, the consumption of coagulating agent per unit of fiber produced may be greatly decreased comweight. pared with the known processes.

TABLE 6 P.O.R.

Elonga- Elonga- Elonga- Elonga- Elonga- Composition of coagulating Maximum Tenacity, tion, Tenacity, tion, Tenacity, tion, Tenacity, tion, Tenacity, tion, bath 1 P.O g. /denier percent g. ldenier percent g. [denier percent g. /dcnier percent g./denier percent 1 1,2-dichloroethane/ethylcne tetrachloride plus ligr'oin. *a-c: Cross-section shown in Fig. 5.

Norm: Spinning solvent: 1,2-dich1omethane/ethylene tetrachloride=65/35. Polymer concentration: 10 percent by weight. Intrinsic viscosity [v]=2.6 (in dichlor'oacetic acid at 0.). Spinning velocity: 50 meters/minute. Nozzle: circular type 0.08 m. /20H Initial concentration of coagulating bath; ethylene tetrachloridejligroin=40 60.

agulating agent consumed per unit of fiber produced is 10 decreased compared with the known processes.

I 8 75 percent in air. It had a silk-like appearance with elegant high lustre. Its tensile properties were as follows:

Tenacity-3.2 grams/ denier Elongation-19.9 percent Similar spinning operations were repeated using various kinds of PMG solution, additives and coagulating agents. The results obtained are summarized in Tables 7 and 7a and the fibers obtained in each case are shown in cross section in FIG. 6.

TABLE 7 PMG solution Spinning solution Polymer concentration, Intrinsic Polymer percent viscosity concen- Solvent by weight l Additwe, content tration Run No 1 1,2-dichloroethane 24. 2. 6 Ethylene tetrachloride, 35... 10 2 Chloroform 21.1 2.5 .do 13 3 Methylene chloride 23. 1 2. 7 Ethylene tetrachloride, 60..- 10 4 1,l,2-trichloroethane 21. 6 2. 3 Carbon tetrachloride, 50; 10 Tetrachlorocthane 19. 9 2.4 Eghdyle rie tet-gchlorgge, 35... 13

. 1, ic oroe ane 6 1,1,2-tr1chlo10ethaue 21.6 2- {Ethylene tetrachlridey 30 10 1,2-dichloroethane-.. 24.0 2.6 Ethylene tetrachloride, 13 8 24. 0 2. 6 1,1,1-tricl1loroethaue, 10 9 Methylene chloride 23. l 2. 7 1,1,l-trichlorocthane, 1O

1 Intrinsic viscosity was measured in dichloroacetic acid solution at 30 0.

TABLE 7a Results Cross- Spinning condition section photo- Tenacity, Elongation Run No. Coagulating agent, content Shape of nozzle, draft graph gJdcnier percent Kerosene 50 1 {Ethylenetetmchlofide, 50 }C1rcula1 cross-section, 3.0- a 3.2 19.9 2 0 }Circular cross-section, 3.5 b 3.1 20. 3 3 o shaped cross-section, 3.0-... o 3. 0 22.1 4 }Circular cross-section, 2.8 d 2. 8 23. 0 5 .{L h 1 so }C1rcular cross-section, 3.0 e 3.3 21.5

ig t oi G "{Ephymne tetrachloride, }C1rcu1ar cross section, 4.0.... i p 3. 1 v 18. 7 7 .do g a a 20.9 8 .{ilLtrichloroethane 3ircu1ar cross-section, 3.3.... h 3. 0 22. 9

igroin 50 i 9 .{lyllktrihlomethanm shaped cross section, 3.0.." 1 2.9 p 24.1

The following further illustrates the present invention. 7

EXAMPLE To a 24.6 percent solution of PMG in 1,2-dichloroethane, which has an intrinsic viscosity [1 of 2.6, eth- 6 ity of 150 meters/minute at a P.O.R. of 3.0 was stretched What we claim is: 1. A process for preparing poly-'y-methyl glutamate fiber of non-circular cross section which comprises:

(a) preparing a spinning solution essentially consisting of poly- -methyl glutamate and chlorinated hydrocarbon including a solvent selected from the group consisting of methylene chloride, chloroform, 1,2- dichloroethane, 1,1,2-trichloroetharie, tetrachloroethane, and mixtures thereof; and

(b) extruding said solution into a coagulating bathconsisting essentially of 10 to 90 percent by weight of an aliphatic hydrocarbon having a boiling point of to 400 C. and a coagulating agent selected.

from the group consisting of carbon tetrachloride, 1,1,1-trichloroethane, and ethylene tetrachloride,

(1) the concentration of said poly-'y-methyl 3111- References Cited tamate in said solvent being suflicient to cause the formation of fibers in said coagulating bath. UNITED STATES PATENTS 2. A process as set forth in claim 1, wherein a com- 3,089,749 5/1963 Ballard 264 203 pound selected from said group of coagulating agents is 5 3,344,219 9/ 1967 Wakasa et al 264178ZL added to said solution prior to said extruding in an 3 371 0 9 2 19 Miyamae 1 2 4 134X amount sufiicient to permit spinning of said fibers at an 3,387,070 6/1968 Wakasa et a1 increased pull-off ratio, but smaller than the amount of said compound which would cause gelling of said solu- JULIUS FROME p i Examiner tion.

3. A process as set forth in claim 1, wherein the 10 Asslstant Exammer amount of said compound in said spinning solution is be- U S C1 X R tween 50 and 90 percent of the amount causing said gelling. 260-318, 78; 264-203 4. A process as set forth in claim 1, wherein said 15 solution is extruded from a substantially circular nozzle. 

